Diet may play a role in immune function, particularly with respect to autoimmunity. Dietary interventions (e.g., antioxidant supplementation, manipulation of the fat content) can prolong survival in murine models of systemic lupus erythematosus (SLE). The role of these dietary factors in the etiology of SLE in humans has not been examined. The objective of this study is to examine the influence of diet on the risk of SLE. We are using data from the Nurses Health Study-I, a cohort of 121,000 women ages 30-55 followed with biennial questionnaire assessment since 1976. In our preliminary analysis of SLE cases occurring between 1980 and 1990, SLE incidence decreased somewhat with higher intakes of Vitamin C and E: rate ratios (RR) and 95% confidence intervals comparing the highest to the lowest quintiles of intake (including supplements) were 0.52 (0.21-1.3) for vitamin C and 0.52 (0.22-1.2) for vitamin E, and tests for trend were p=0.20 and 0.36, respectively. This was not seen when we excluded supplement users: for vitamin C, RR=1.1 (0.42-2.8) and for vitamin E, RR=0.89 (0.36-2.2). There was little evidence for an association with vitamin A or total fat intake. Efforts are currently underway to identify and verify SLE cases diagnosed in 1992-1996 in the NHS-I and NHS-II cohorts. - autoimmune diseases, systemic lupus erythematosus, risk factors, antioxidants, ascorbic acid, retinol, tocopherol, fat, omega-e - Human Subjects & Human Subjects: Interview, Questionaires, or Surveys Only